Typical product of all to date known methods for spinning of solutions or melts of polymers in an electric field using static needle spinning electrodes (nozzles, capillaries, etc.) or needleless spinning electrodes (rotating cylinder, cord moving in a direction of its length, rotating coil, coated cord, etc.) is planar layer of randomly interlaced nanofibers of the same polarity. Such a layer has in combination with other supporting or covering layers number of applications, namely in the field of filtration and hygienic means, but on the other hand, for number of other applications, as well as for further processing by standard textile technological methods is its usage rather limited. That is because these applications prefer linear formations from nanofibers, or more complex three-dimensional structures created by processing of such linear formations.
In this sense, for example US 2008265469 describes a method of production of linear formation from nanofibers which is based on the principle of direct drawing off of nanofibers from several pairs of against each other arranged nozzles having electric charges of opposite polarity, and subsequent connection of these nanofibers. This only leads to low production output, which is moreover not constant, due to mutual influence of the electric fields of individual nozzles. Thus the resulting linear formation has considerably non-uniform and accidental structure as well as low tensile strength, thanks to which this method is suitable only for experimental use in laboratory.
US 20090189319 describes a method for fabrication of linear formation from nanofibers by twisting a planar layer of nanofibers formed by electrostatic spinning. Linear formation created in this manner, has also only limited tensile strength and is not suitable for practical use. In addition, the method of twisting the planar layer of nanofibers is technologically relatively complicated and time-consuming, achieving only low productivity, and so this method is applicable only in limited laboratory scale.
Another possibility for fabrication of linear formation from nanofibers is by using collecting electrode according to WO 2009049564, which in one of the described embodiments comprises a system of singular electric charges arranged on an abscissa or on the circumference of rotating disc. Created nanofibers are hereat deposited preferably along these electric charges, thus forming linear formations. Tensile strength of formations fabricated in this manner may be higher than that of the formations fabricated according to any of the preceding methods, but still insufficient for practical applications. Another drawback of this method is relatively small length of fabricated linear formation from nanofibers achievable, as it is limited by the maximum possible length of the collecting electrode. For this reason, this method, too, cannot be successfully used in industrial scale.
The goal of the invention is to eliminate or at least to reduce the disadvantages of the background art and to propose a method for production of nanofibers, which would enable fabrication of linear formation from polymeric nanofibers which could be further utilized or processed by standard textile technological procedures, the method maintaining sufficient productivity and applicability in an industrial production.